1. Field of the Invention
The present invention relates generally to insect control systems and vapor exhaust systems for structures, and more particularly, but not by way of limitation, to an improved system for both selectively injecting pesticide beneath a structure and extracting fluids, such as water and harmful vapors from beneath the structure.
2. Brief Description of the Related Art
Numerous systems have been proposed for protecting buildings and homes from damage caused by pests, such as subterranean termites, which can do considerable structural and cosmetic damage over time. A common practice for treating infestation of pests into a structure is to pretreat the ground under the structure with pesticide chemicals during the construction process. This is done by applying a substantial quantity of pesticides, such as termiticide, on the ground under the proposed structure before the slab is poured in an attempt to create a chemical barrier that will keep the insects from entering the structure.
The problem with this method of treatment is the amount of pesticide required to be used can be harmful to occupants of the structure as well as harmful to the ground water. Furthermore, even though a large amount of pesticide is applied to the ground, the resulting chemical barrier nevertheless becomes ineffective over time as the chemicals break down.
With these problems in mind, other methods have been developed for the periodic injection of pesticide beneath structures. One particular method involves the drilling of holes in around the slab for the injection of pesticide. This method has many drawbacks which include affecting the integrity of the slab, the mess of drilling through the slab, convenience of having to clear a path around the structure to permit access for the drilling, the need for the holes to be plugged, and the residual odor of the pesticide that escapes during the injection process. In addition, this process must be periodically repeated during the lifetime of the structure.
Considerable efforts have been made to alleviate the problems of post construction periodic injection of pesticides beneath the structure by placing a injection system beneath the structure during the construction process. Many of these systems involve placing a network of porous tubing beneath the structure. The problem encountered in these systems however is that the holes provided in the tubing have a fixed diameter and thus are susceptible to clogging. That is, because the preference to place the network of tubing within the fill material positioned under the slab, the fill material often obstructs or clogs the holes. The holes can also get clogged by dead insects and other pests that may enter the holes in the tubing over the course of the lifetime of the system. When the holes become clogged or obstructed, they fail to deliver pesticide to the surrounding location, thereby creating a gap in the chemical barrier which can be exploited by pests.
Other injection network systems with fixed holes have attempted to prevent hole obstruction elaborate systems or by varying construction procedures. For example, systems have been developed where the holes are sheltered with wick-like membranes, soil screens, shower-type sprinkler heads, and sponges. Other systems attempt to keep the holes from being obstructed by surrounding the holes with specialized fill materials applied during the construction process. Each of these types of systems is complex and increases installation costs.
Another problem of concern in many regions of the country is accumulation of moisture and/or harmful gases, such as radon, beneath homes and other structures. The accumulation of water beneath a floor slab can be a substantial problem, particularly where the water table is high or rainfall is plentiful. The accumulation of water beneath the slab of a structure can result in the seepage of water through the foundation and into the structure. In addition, the water is a breeding ground for microorganisms, such as mold and mildew, and may also cause the foundation to erode.
Radon is produced by the gradual decay of solid radioactive elements in the soil. While geographic regions that contain large concentrations of solid radioactive elements in the soil, the mere release of the gas even in these areas is not a concern in that the uninterrupted movement of radon into the atmosphere is generally at such a slow rate that little or no health hazard is posed.
The concern has risen in recent years due to the discovery of large concentrations of radon gas that had accumulated in dwellings. It became apparent that it was not the rate at which radon gas was given off by the soil, but the failure of dwellings to allow radon and other contaminants to continue on into the atmosphere. This has been caused by the effort of builders to make homes more energy efficient by thermally sealing the structures as tight as possible.
One factor in the degree of gas accumulation is the construction of the building itself and more specifically the construction of the support system in contact with the ground. That is, more and more homes are being built upon what is called a slab foundation. The effect of this type of foundation is to act as a cap to contain gases from the soil, allowing them to escape only when they find their way up into the house by the way of the cracks and plumbing openings formed in the slab.
Numerous subsurface ventilation systems have been proposed. However, like the prior art pesticide systems discussed above, these ventilation systems are susceptible to clogging, are relatively complex, and expensive to install. In addition, the prior art ventilation systems are not adapted to serve a dual purpose of periodically delivering pesticides beneath the structure.
To this end, a need exists for a subsurface pesticide injection and fluid extraction system which is simple in design, inexpensive to install, and easy to operate and maintain. It is to such a system that the present invention is directed.
The present invention is directed to a subsurface pesticide injection and fluid extraction system in combination with a structure. The structure has a footing formed in a base soil, a stem wall formed on the footing and defining a perimeter of the structure, a fill material disposed on the base soil within the perimeter of the stem wall, and a concrete slab formed on the fill material. The concrete slab has openings extending therethrough. The subsurface pesticide injection and fluid extraction system includes a tubular conduit disposed within the fill material of the structure such that portions of the tubular conduit are disposed adjacent the openings of the concrete slab. The tubular conduit has a sidewall, a first end, a second end, and a plurality of pores extending through the sidewall of the tubular conduit.
A connector member is attached to one of the first and second ends of the tubular conduit and is detachably connectable to a source of pressurized pesticide such that pesticide may be selectively injected into the fill material in a injection mode to form a chemical barrier against the infestation of pests into the structure through the openings of the concrete slab. The connector member is also detachably connectable to a vacuum source such that fluids may be selectively extracted from the fill material in an extraction mode to reduce the passage of fluids into the structure through the openings of the concrete slab.
The tubular conduit has a substantially circular cross-sectional configuration and is constructed of an elastomeric material such that upon applying a positive internal pressure to the tubular conduit by the injection of the pressurized pesticide into the tubular conduit the pores of the tubular conduit are caused to open to permit the release of pesticide from the tubular conduit into the fill material in the injection mode while the tubular conduit maintains its substantially circular cross-sectional configuration. Upon applying a negative internal pressure to the tubular conduit the pores of the tubular conduit are caused to open to permit the drawing of fluid from the fill material into the tubular conduit in the extraction mode while the pores remain substantially clog free and the tubular conduit maintains its substantially circular cross-sectional configuration. Finally, upon removal of the positive and negative internal pressures the pores are caused to close so that the pores remain substantially clog free while the tubular conduit maintains its substantially circular cross-sectional configuration.